--cache-clear: add test for keeping non-supporting files
--cache-clear: add test for keeping non-supporting files

Ref: https://github.com/pytest-dev/pytest/pull/6296

The-Compiler/pytest,The-Compiler/pytest,nicoddemus/pytest,nicoddemus/pytest,alfredodeza/pytest,pytest-dev/pytest,markshao/pytest,RonnyPfannschmidt/pytest,Akasurde/pytest